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Deploying 87 Satellites in One Launch: Design Trades Completed for the 2015 SHERPA Flight Hardware

Deploying 87 Satellites in One Launch: Design Trades Completed for the 2015 SHERPA Flight Hardware

SSC15-II-2

Deploying 87 in One Launch: Design trades completed for the 2015 SHERPA hardware

Kaitlyn Kelley, Mitch Elson, Jason Andrews Services 3415 S 116th St #123, Tukwila, WA 98168; (801) 618-7223 [email protected]

ABSTRACT Launch remains an obstacle for small satellites, which are often limited to small platforms, aft bulkheads, and accommodations for a single P-Pod. While launch have expanded the available to small satellites, the largest number of satellites deployed in a single launch stands at thirty-seven. Spaceflight has secured a single launch in 2015 for no less than 87 small satellites. The ability to support so many satellites stems from tactical design decisions. This paper focuses on the design trades for the adapters developed for the 2015 SHERPA launch. Three unique payload adapters were designed to interface to the Moog ESPA Grande ring, the core of the SHERPA . Each is an aluminum plate that interfaces to the 24” bolt-hole pattern on the five ESPA Grande ports. For these adapters, a balance was struck between designing to the unique payload in the flight configuration and developing a reusable system. The paper discusses the initial design trades regarding the adapter plate capabilities and how these trades have affected the plates’ utility on later SHERPA missions.

INTRODUCTION capacity for adapter equipment and offer more options Spaceflight Services is poised to break the record for for creative integration. With this additional volume the most satellites launched on a single launch , and capacity, the record number of satellites in a single doubling the number previously launched. launch is primed to be broken.

As more small satellites clamor for launch, many 2015 SHERPA MISSION organizations have begun filling excess capacity with The 2015 SHERPA mission addresses the limitations of small satellites and nanosatellites. Innovative Solutions current launch configurations by maximizing the in Space B.V. and Tyvak Nanosatellite Systems have number of integrated to the structure. It is an been launching nanosatellites as secondary payloads for ESPA Grande-derived deployment system years. Nanosatellite deployment has even begun from intended for launch on any Evolved Expendable the International , through the commercial (EELV). The SHERPA is a free‐flier company NanoRacks. auxiliary payload deployment system capable of NASA and the U.S. government also launched large deploying up to 1500 kg. Secondary payloads are numbers of small satellites in the past. The integrated to each port of the SHERPA and the primary Operationally Responsive Space office recently payload can be safely integrated to the top of SHERPA. launched 29 on a Minotaur launch vehicle. Flight Configuration , a Russian agency, develops cluster missions around a few main payloads and fills the While the high number of satellites on this mission is in remaining space with small satellites and nanosatellites. part due to CubeSat constellations, the SHERPA concept is well suited to support small spacecraft that There is an upward trend in the number of satellites range from CubeSats to 300kg. By developing unique deployed during each launch. Moving from one adapters for the standard ports, Spaceflight has enabled satellite to nearly forty is a huge advance. Spaceflight many different sizes of spacecraft to deploy from Services is poised to take the next leap; from forty to SHERPA, including the DARPA eXCITe nearly ninety satellites deployed in a single launch. microsatellite, built by NovaWurks, and two BlackSky Unlike the other commercial companies mentioned, Global Pathfinder satellites. Future planned which focus primarily on CubeSats, Spaceflight configurations involve multiple SHERPA rings on a integrates microsatellites as well. This ability opens up single launch as well as support for much larger new opportunities for integration on spacecraft on the forward section of the SHERPA ring. larger vehicles. These larger launch vehicles have more

Kelley 1 29th Annual AIAA/USU Conference on Small Satellites For the 2015 SHERPA mission the final configuration For microsatellite deployments, Spaceflight has incorporates three microsatellites and 84 CubeSats of selected the Planetary Systems Corporations Motorized which the majority are 3Us. The microsatellites LightBand as our preferred separation system. represent two different spectrums with regard to mass Planetary Systems has developed and published and interfaces. This demonstrates the capabilities of standards for mechanical and electrical interfaces. using the modular approach Spaceflight took in the Spaceflight offers our services at fixed prices, so known design and implementation of its adapter hardware. technical specifications and cost allow Spaceflight to have a high degree of confidence in its pricing. With extensive flight heritage, the Motorized LightBands provides confidence in its mission assurance. That is further enhanced by the amount of testing that Planetary Systems has completed. The company provides the related data in their published documentation.

Finally, the Motorized LightBands have compiled a great deal of data on their deployment characteristics based on their extensive flight heritage. This supports another part of overall mission assurance, and provides the customer with the knowledge that their spacecraft will have minimal tip-off rates. This is an important factor in our post-deployment system stabilization and allows Spaceflight to deploy spacecraft as soon as possible after launch.

Figure 1: 2015 SHERPA Flight Configuration In addition to the microsatellites, there are 84 CubeSats One of the innovative microsatellites included on the manifested on the 2015 SHERPA. Spaceflight chose to manifest is a 160kg system, developed and flown by use the QuadPack, a CubeSat deployment system NovaWurks. Based on our current customer inputs, this procured from Innovative Solution in Space of the 125kg to 250kg spacecraft class will be an area of high Netherlands, to deploy the CubeSats. The “Quad” in demand. Spaceflight has concluded that this is one of QuadPack refers to the baseline configuration to the worst served markets in terms of access to space. support four 3U CubeSats. This can be configured to Historically, this category was served by foreign launch support any number of CubeSats that can be divided service providers and the U.S. Government. As into that space. For the 2015 SHERPA mission advances, this class of spacecraft has begun Spaceflight is utilizing the modularity to fly a number to catch the interest of commercial satellite providers. of 6U CubeSats. This new group of customers does not have access to the Government small launch vehicles, and, to date, Not only do the QuadPacks provide modularity in the commercial small launch vehicles are too expensive for CubeSat configuration, the ability to integrate the the secondary market. While there are efforts underway system through multiple bolt hole patterns enables to develop lower cost commercial small launch additional integration options. Spaceflight has designed vehicles, the efficiencies in cost provided by the an adapter plate that integrates the aft end to the plate. SHERPA concept will remain a competitive means to This design allows Spaceflight to place seven access popular . QuadPacks per SHERPA port.

Two microsatellites on the 2015 SHERPA mission The QuadPacks are compatible with CubeSats support the early phases of a constellation build out. developed to the Cal Poly CubeSat Standards. This With numerous spacecraft manifested on this mission system also offers options to support some of the Spaceflight has had to consider not only the mass to emerging trends in the CubeSat world; such as “tuna , but also the volume consumed by any given can” extrusion, and volumegrowth around the rail spacecraft. By developing an adapter system that system. places two spacecraft on a single port, Spaceflight is able to maintain its Internet advertised pricing. Mission Concept of Operations Customers can recognize the benefit of this pricing by A significant driver for the requirements of the 2015 designing to industry and SHERPA published SHERPA mission is the overriding concept of avoiding standards. This will increase the number of rideshare any additional risk to the primary spacecraft or the opportunities available and keep the cost per kg low. launch vehicle. Secondary payload mechanical and

Kelley 2 29th Annual AIAA/USU Conference on Small Satellites electrical designs have been addressed over the years at • 45 minute payload deployment time the Small Satellite Conference; therefore it will not be discussed in this paper. • Continue to relay over selected ground sites until end of battery life The SHERPA is to be separated from the launch approximately 10 hours post SHERPA vehicle prior to any deployments. This operation separation. enables Spaceflight to minimize the risk to the launch service provider because it is responsible for all deployments after SHERPA separation.

This separation requirement drove Spaceflight to develop a robust avionics system at a competitive price. The avionics system had to be compatible with Spaceflight’s advertised launch pricing. In the end, we determined that developing our own system was the best solution.

The avionics incorporated into the 2015 SHERPA mission were kept as simple as possible and still meet mission requirements: battery, computer/sequencer, Figure 2: 2015 SHERPA Event Timeline GPS and transmitter. The SHERPA system is powered off throughout the launch ascent phase (as a secondary FLIGHT HARDWARE DESIGN TRADES payload itself) and activated via the separation event from the upper stage of the launch vehicle. Once Deployment Electronics initiated, the avionics perform the separation sequencing based on a timing script. A common challenge in is defining a set of requirements that can be met through “off the shelf” Timing the separation events was an important trade solutions. In the case of the SHERPA, Spaceflight analysis. The first consideration was to avoid developed electronics capable of meeting mission spacecraft re-contact. The second was to manage the requirements. Requirements included the electrical forces imparted on the SHERPA because there is no inhibits required by the launch service provider to system to maintain and control attitude. The third ensure no inadvertent deployments. requirement was to deploy all the satellites and confirm the deployments prior to the end of battery life. Our analyses and lessons learned are documented for use in future mission planning. We have developed a separation plan that minimizes risk of contact and does so without control authority on the SHERPA. Figure 3: Internal view of SHERPA showing Spaceflight also included a GPS for position knowledge electronics and a to transmit telemetry as part of the Power is a considerable challenge when there are 87 SHERPA. Avionics will capture the GPS location of spacecraft being deployed. Both the GPS and radio each separation event, and confirm deployment. The must be powered, for up to 10 hours. The design avionics provide the telemetry data to customers within solution Spaceflight selected was the CORTEX 30 minutes of successful . Avionics Suite. The CORTEX battery is a Spaceflight COTS unit based on -ion cells purchased from The overall mission timeline is as follows: Yardney. • Separation from the upper stage of the launch Spaceflight also chose to keep the flight computer, or vehicle sequencer, in house. The CORTEX 160 flight computer performs the computing, command and • Avionic system initiated and mission sequence storage functions needed for the mission. timing begins

• 30 minute coast – no SHERPA activity

• Enter payload deployment sequence

Kelley 3 29th Annual AIAA/USU Conference on Small Satellites Motorized LightBand. It is also capable of supporting a total mass of up to 150kg.

The plate itself is machined from one piece of aluminum alloy. The diameter is just slightly wider than the 24-inch bolt pattern at 25.75 inches; it has a total mass of 13.3kg. In addition to supporting the spacecraft, the backside of the plate is used to mount the various avionics components required for the 2015 SHERPA mission. The plate has accommodations for cable pass through. Figure 4: CORTEX 160 Spaceflight’s final piece of in-house capability is the The dual port adapter enables Spaceflight to fully newly developed Spaceflight Ground Station Network. utilize the volume available on a port and supports two between the SHERPA and ground spacecraft, each with a mass of up to 85kg. This station are primarily accomplished using Spaceflight adapter is machined from a single piece of aluminum Networks. The system will be a global ground station and has a mass of 21.7kg. It attaches to the ESPA network developed to support commercial and Grande ring via the 24 inch bolt hole pattern and has government satellites. It is available to Spaceflight accommodations for both the 11.732 inch and 8 inch customers on a pay per-minute basis. The network has Motorized LightBands. a “bent-pipe” architecture: all ground stations are unmanned and controlled by the central network operations center located in Seattle, WA. The ground stations are connected via terrestrial fiber, and customers are given direct access (via TCP/IP) to communicate with their spacecraft during the designated communications window. Spaceflight Networks currently support communications in UHF, S, and X-bands. For commercial spacecraft, S-band uplink and X-band downlinks are used. For the 2015 SHERPA mission, Spaceflight will use three of the Figure 5: Dual Port Adapter ground stations as well as support from NASA to downlink the mission telemetry. CubeSat Adapters

Microsatellite Adapters To date Spaceflight has flown over 76 CubeSats across a range of launch systems using a variety of different Spaceflight developed two requirements that defined dispensers. With no slowdown in upcoming the final design of the adapter plates; modular and deployments forecast the QuadPack Plate was minimal mass. Overall mass is a significant concern in developed. It supports 7 QuadPacks per plate. the business of purchasing excess launch capacity and then selling that capacity to satellite providers. The final designs are machined aluminum plates with the minimal mass required to support the flight configuration payloads under the anticipated launch load.

For the 2015 SHERPA mission, Spaceflight is using 3 different plates and in total allows for 6 different satellite, separation or dispenser configurations. These plates are estimated to support 80% of the current customer base Spaceflight tracks.

The radial port adapter is a flat plate for microsatellites Figure 6: QuadPack Plate greater than 50kgs. It bolts directly to the SHERPA 24 inch port interface and can provide separation diameter interfaces of either 11.732 inches or the 15 inch

Kelley 4 29th Annual AIAA/USU Conference on Small Satellites extremely expensive; costs can exceed $500,000.00 for the minimum time allowed..

Spaceflight solved these issues using a different, yet pragmatic and efficient approach. Spaceflight will integrate the SHERPA into the integrated payload stack, at the Spaceflight facility near Seattle Washington.

One challenge to this approach is the logistics and cost of shipping to the launch site. While our approach is no different than that of shipping individual satellites overland, the most difficult aspect of this approach has turned out to be the Department of Transportation requirements with respect to shipment of hazardous materials. In this case, the identified hazards are the Figure 7: QuadPack Plate integrated with multitude of lithium ion batteries and several dispensers and electronics pressurized vessels. Although working through the The initial SHERPA is based on the ESPA Grande ring, hazards is time-consuming, Spaceflight will save a along with a number of adapters, which are paired with significant amount when compared to the cost of Spaceflight Systems electronics. The concept behind renting a facility at the launch site. SHERPA is to make the configuration modular. With Our facility, created on a tight budget, complies with this set of adapters and electronics Spaceflight can mix the basic needs of our customers and launch service and match components to suit most any set of payloads. provider. Our facility is Class 100K. We’ve also HARDWARE DELIVERY AND INTEGRATION invested in hardware that supports our customer’s integration logistics. In the past two months, The paper will close with a status report on the 2015 Spaceflight completed a 725 square foot integration SHERPA mission. As of the paper submittal date,. area for about the price of a car. This area is Class Spaceflight is preparing for final integration, which will 100K compliant and includes a gantry crane. This begin late this summer. Integration will cover a 45-day demonstrates what can be accomplished when you period and will consist of completing final integration solve the requirement instead of implementing the most of the payloads, shipping to the launch site and final commonly aerospace solution. launch vehicle integration.

Integration Facilities Spaceflight defined a new approach to assembling an integrated payload stack such as SHERPA. Being a scrappy start up drives an innovative approach to .

Spaceflight was founded on the concept of providing a service to an underserved market: small satellite launch. Spaceflight has developed the hardware, processes, and overall CONOPs within a small budget. Figure 8: Newly completed Class 100K processing This small budget had to support use or the room development of an integration facility for SHERPA. Typically, integration activities take place at the launch Finally, a point on how hardware is handled during site, either at the launch service providers’ facility or integration CONOPs. Spaceflight started with a clean other launch base facilities. There were two limiting slate and worked with our partner LoadPath to develop factors for Spaceflight. First, the launch service a simple system of handling equipment capable of provider has a primary customer, with full access to supporting not only the 2015 SHERPA mission, but their payload processing facility, severely limiting the also an estimated 90% of the payloads that may fly on a time available for any secondary payloads. Second, SHERPA system in the future. commercial facilities located at or near the launch are

Kelley 5 29th Annual AIAA/USU Conference on Small Satellites The ground support equipment is configured in such a way that Spaceflight is able to handle adapter integration to payloads in both a horizontal and vertical configuration. This provides a great deal of versatility for our customers for their own spacecraft checkout and final preparations.

On our upcoming 2015 SHERPA mission, the QuadPacks will be integrated to the adapter while in the horizontal configuration. Once complete, the adapter plate with the QuadPacks will be mounted to the SHERPA and the CubeSats will be loaded. This reduces the number of operations where loaded QuadPacks will be handled, lowering risk of damage to the individual CubeSats. Figure 9: SHERPA fit check with volumetric models

This same flexibility is used in the CONOPs for Schedule handling and integrating the microsatellites. When utilizing a mix of in-house and commercial off Focusing on simple solutions to solve complex the shelf components, organizing the delivery schedule integration challenges led to the development of can be a complex task. Some items have been available CONOPs that minimize risk and cost. This approach is for years. In house products have EDU’s available for now the standard that Spaceflight uses in the testing. Other flight hardware is delivered just in time development of subsequent missions maintaining the for the launch, in order to minimize time spent in ability to provide cost effective launch service support storage. to our customers. The ESPA Grande ring has been on site for quite some time. As of June 1, 2015, all of the adapter plates have arrived and been verified for fit. Planetary Systems has Fit Check delivered the 3 Motorized LightBands for the microsatellites. One of the first major milestones we completed was the mechanical fit check between the SHERPA, the upper stage of the launch vehicle, and the interface to the primary . The fit check was also used as an opportunity to test out the processes and handling equipment, further reducing mission risk.

The mechanical fit check was a success. Spaceflight demonstrated that the hardware fit and the handling equipment was built appropriately. Additionally, a set of volume simulators was produced. These volume simulators allowed the team to assess the access, or lack thereof, to the SHERPA when fully integrated with Figure 10: Flight QuadPack Plate payloads. While it seems simple, the addition of the volume simulators helped refine procedures, consequently avoiding time loss during the launch campaign.

Figure 11: Flight dual payload adapter

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Figure 12: Flight radial plate adapter Avionics and software are going through test. They have already demonstrated their capability to send deployment signals to the QuadPacks.

All that remains are a few ground support items and the QuadPacks. These are all scheduled to arrive by August, leaving Spaceflight with a comfortable schedule margin prior to the first spacecraft arriving at the end of October for integration.

FUTURE SHERPAS There are several future SHERPA missions in the works, one in 2017 and two more in 2018. While Spaceflight is maintaining adherence to the standards adopted from industry, there are expected upgrades.

Propulsion is a key enabler for the SHERPA concept. Spaceflight is developing a plan to implement a series of SHERPAs with increasing delta V capability to support missions requiring altitude change and long- term orbit maintenance.

In addition, the SHERPA serves as the perfect platform for hosted payloads. It is unique in its hosting capability, as the essentially gets a dedicated spacecraft bus following secondary payload deployment. This means that the hosted payload is actually the primary payload with full access to power, pointing and .

SHERPA is based on the ESPA Grande ring, but the concept is tailorable to any number of adapter concepts. In 2015, Spaceflight began to explore adapters that provide additional configurations and mass saving features that will only enhance Spaceflight’s ability to successfully manifest secondary payloads, taking advantage of the wealth of excess lift capacity that has gone unused for years. Time will tell what the future capabilities of SHERPA will be after its historical first launch in 2015.

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